On the geodesic midrange crossing constant
Abstract
We introduce an analytic framework for studying the number of crossings in planar straight-line and spherical geodesic drawings; we begin by analyzing drawings in a continuous setting and then pass to finite graphs. We use this approach to derive multiple results. First, we show that the midrange crossing constant is strictly smaller than 8/(9π2), improving the best known upper bound of Pach and Tóth from nearly thirty years ago. Second, we prove sharp lower bounds for some restricted drawing classes. For spherical geodesic drawings with uniformly distributed vertices, we determine the minimum number of crossings at every edge density. We also prove lower bounds for planar straight line drawings in compact convex domains with uniform vertex sets. Consequently, we determine the restricted midrange crossing constant to be 8/(9π2) in both of these settings. Finally, for two-layer bipartite drawings, with straight edges between two parallel lines, we determine the midrange crossing constant to be 2/3.
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BibTeX
@misc{lepsveridze2026geodesic,
title = {{On the geodesic midrange crossing constant}},
author = {Saba Lepsveridze and Oriol Solé-Pi},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2605.16700},
eprint = {2605.16700},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.16700},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - On the geodesic midrange crossing constant
AU - Saba Lepsveridze
AU - Oriol Solé-Pi
PY - 2026
DA - 2026/11/03
PB - arXiv
DO - 10.48550/arxiv.2605.16700
UR - https://arxiv.org/abs/2605.16700
AB - We introduce an analytic framework for studying the number of crossings in planar straight-line and spherical geodesic drawings; we begin by analyzing drawings in a continuous setting and then pass to finite graphs. We use this approach to derive multiple results. First, we show that the midrange crossing constant is strictly smaller than 8/(9π^2), improving the best known upper bound of Pach and Tóth from nearly thirty years ago. Second, we prove sharp lower bounds for some restricted drawing classes. For spherical geodesic drawings with uniformly distributed vertices, we determine the minimum number of crossings at every edge density. We also prove lower bounds for planar straight line drawings in compact convex domains with uniform vertex sets. Consequently, we determine the restricted midrange crossing constant to be 8/(9π^2) in both of these settings. Finally, for two-layer bipartite drawings, with straight edges between two parallel lines, we determine the midrange crossing constant to be 2/3.
ER -